TiO_(2)/MWCNTs光催化氧化法深度处理焦化废水生化尾水

Advanced Treatment of Biologically Treated Coking Wastewater by TiO_(2)/MWCNTs Photocatalytic Oxidation

文章采用简单的溶胶凝胶-物理负载法制备了TiO_(2)/MWCNTs复合光催化剂,利用傅里叶变换红外光谱、扫描电子显微镜、透射电子显微镜、X射线衍射和紫外-可见漫反射光谱等表征方法对TiO_(2)/MWCNTs的物理化学性质进行了表征,并将其应用于H_(2)O_(2)协同光催化氧化法深度处理焦化废水生化尾水中。结果表明,TiO_(2)主要为锐钛矿相,MWCNTs掺杂后降低了TiO_(2)的禁带宽度。MWCNTs掺杂量(MWCNTs/TiO_(2)质量比)为0.50%时,TiO_(2)/MWCNTs的光催化活性最高,H_(2)O_(2)的加入显著提高了光催化氧化效率。TiO_(2)/MWCNTs投加量为1.0g/L,H_(2)O_(2)的投加量为1.5mL/L,废水初始pH值为3,反应时间为150min时,焦化废水生化尾水的COD、UV_(254)、色度、TOC的去除率分别为65.22%、88.71%、89.74%和46.56%。自由基捕获实验表明,·O_(2)是光催化氧化过程中最主要的活性组分。TiO_(2)/MWCNTs经5次重复使用后,对焦化废水生化尾水COD和UV_(254)的降解效率仍然可以达到67.49%和83.83%,表明催化剂稳定性良好。

TiO_(2)/MWCNTs composite was prepared through hydrothermal-immobilization method and the physicochemical properties were characterized by the Fourier transform infrared spectroscopy(FT-IR),the scanning electron microscopy(SEM),the X-ray diffraction(XRD)and the ultraviolet visible diffuse reflectance spectroscopy(UV-vis DRS)techniques.Then the composite was applied to degrade bio-treated coking wastewater by H_(2)O_(2) synergistic photocatalytic oxidation.The results showed that TiO_(2) was mainly anatase phase and the introduction of MWCNTs reduced the band gap of TiO_(2).The photo-catalytic activity of TiO_(2)/MWCNTs reached the maximum when the mass ratio of MWCNTs/TiO_(2) was 0.50%.The addition of H_(2)O_(2) greatly improved the photocatalytic oxidation efficiency.When the dosage of TiO_(2)/MWCNTs was 1.0 g/L,the dosage of H_(2)O_(2) was 1.5 m L/L,the initial p H value of wastewater was 3 and the reaction time was 150 min,the removal rates of COD,UV_(254),color and TOC of bio-treated coking wastewater were 65.22%,88.71%,89.74%and 46.56%,respectively.Free radical capture experiments showed that·O_(2)was the most important active component in the process of photocatalytic oxidation.The removal rates of COD and UV_(254)could still reach 67.49%and 83.83%after 5 cycles,indicating that the catalyst had stable properties with good reusability.